Arteriosclerosis is the number one killer in the United States. Close to one million deaths occur annually from heart disease, hypertension and stroke caused by "hardening of the arteries" which inhibits the vital blood supply to the heart muscle, brain, and other tissues. Very often coronary artery disease results from the buildup of ateroscleratic plaques on the inner walls of the arteries which supply blood to the heart muscle. These plaques often contain cholesterol and other materials. They may also become hardened by calcification and become sites for the formation of blood clots which further obstruct blood flow through the arterial system. This debilitating process also occurs in many of the arteries of patients with this disease often resulting in blockage of the carotid arteries to the brain causing strokes.
Arteries attacked by arteriosclerosis are not only narrowed or blocked by the buildup of plaque but also become less elastic as compared to healthy arteries. This condition is frequently described as "hardening of the arteries". Healthy arteries are highly elastic and as the heart pumps blood into the arterial system the arteries expand to receive the increased volume of blood being pumped into them by the heart. As the heart relaxes during diastole (i.e., the filling phase) the normal elasticity of the arteries causes them to contract or decrease in volume thereby forcing blood into and through the capillaries. The natural elasticity of the arteries is known as arterial compliance and provides a blood reservoir for the arterial system into which the heart ejects each stroke volume of blood. By reason of the elastic characteristics of the arterial system, each blood vessel stores energy absorbed during the systolic action of the heart which maintains blood flow between heart beats. When arterial compliance is inhibited or dampened by disease both of these functions (i.e. volume storage and energy storage) are seriously impaired. A condition of decreased arterial compliance requires higher systolic blood pressure to achieve an equivalent blood flow and the effective work load on the heart itself is increased.
Arterial compliance is also extremely important in supplying the proper flow of blood to the heart muscle itself. During systole, blood flow through the coronary arteries is reduced because the myocardium, or heart muscle, is contracting thereby constricting or mechanically "squeezing down" the small arteries and capillaries and limiting the flow of blood through them. During diastole the myocardium relaxes and the small arteries and capillaries located therein open so as to sustain increased blood flow. The compliant aorta and coronary arteries act both as a reservoir for holding the blood which must be pushed through the heart muscle during diastole and, by reason of the energy stored in the walls of these vessels, effectively pump blood through the myocardium during diastole.
With the onset of arteriosclerosis the natural elasticity and compliance characteristics of the arterial system are diminished thereby restricting blood flow and increasing the work load of the heart.
Presently available surgical treatments to overcome this debilitating condition typically involve procedures to either remove the plaque from the inner walls of the vessels or provide blood flow around the plaque through the use of bypass grafts. The first procedure is known as coronary endarterectomy whereby the plaque material which has built up in the larger branches of the coronary arteries is surgically removed. This procedure is time consuming and relatively difficult and does not effectively repair or "clean out" the smaller arteries. Hence, it is infrequently performed and when performed, it is often only with limited success. The second procedure is known as coronary artery bypass grafting which uses vein or artery grafts to supply blood to the coronary artery beyond the site of major obstruction. This procedure is presently used in approximately 250,000 cases per year in the United States alone. Yet another surgical treatment is coronary angioplasty which involves removing or "pushing" the plaque out of the way with a small balloon catheter. Each of these procedures is designed to increase the flow of blood to the heart muscle by eliminating or bypassing obstructions in the coronary arteries.
A need exists for a more efficient and effective method to increase and stabilize blood flow through the arterial system and to decrease the work load on the heart itself without the difficulties and shortcomings attendant to presently known methods of treatment. By the present invention this need has been recognized and satisfied.